People often ask if hydroponic crops are as nutritious as those grown in the field, or how they can get everything they need without soil. Hydroponic systems are not recirculating only water, rather a nutrient solution from which plants take up 13 of the 16 essential nutrients they require. This produces incredibly high-quality crops with high nutritional value, and in some cases higher vitamin and mineral level compared to soil grown.

In commercial systems, inorganic nutrient salts are widely used. These are dissolved into water at varying concentrations, based on the crop and stage of growth. These nutrients are extremely easy to work with, deliver nutrients in bioavailable forms, and allow for high controllability of the nutrient constitution of the solution. This is especially advantageous in recirculating nutrient solutions, to ensure what is needed can be added.

Many hydroponic systems use auto-dosers to inject stock solutions as they are taken up by plants, based on the electrical conductivity of the solution (EC). Rather than only measuring electrical conductivity, technology is moving toward using ion selective electrodes (ISEs) to manage the solution. ISEs measure the concentration of an individual ion in the solution, and injectors can respond as nutrients are taken up. Currently, to reliably determine the amount of each nutrient in the solution, water samples should be taken and sent to a lab for analysis. This allows for any specific adjustments to be made manually to nutrient solution. 

Although these technologies are extremely costly, due to the expensive instrumentation, they provide potential for highly-controlled nutrient solutions. Theoretically, if a recirculating system is well-managed, it will not have to be flushed and it contributes to an overall reduction in water and fertilizer inputs. This is incredibly important in contributing to the overall sustainability of hydroponic food production.

A large downfall of inorganic nutrients is their production process.  Inorganic nutrients require building block materials, which often come from mining operations, or are synthesized from high energy reactions. Many of these processes are incredibly energy intensive which contribute to the lifecycle of production. Comparatively, organic nutrients can be used in hydroponic production. These include liquified seaweed, compost tea or processed chicken manure, or in the case of hydroponics, fish byproducts from fish living in the system. Organic nutrients contribute to a circular economy and require less energy to produce, but they are much trickier to work with than inorganic nutrients.

Organic nutrients contain carbon along with other essential minerals, because of this microbes in the solution are required to break down compounds into mineral forms plants can take up. Organic nutrients also offer less overall control for specific nutrients in solution, and generally have a lower concentration of nutrients. In general, studies have found lower yields when using organic nutrients. There is potential for organic nutrients to be applied more widely and potentially alongside inorganic nutrients to produce high quality products with lower life cycle impacts.

Source: Agronomy

Overall, inorganic nutrients used in hydroponic food production allow growers to have a good user experience while maintaining a high level of control over the nutrients being provided to plants. With higher levels of instrumentation, the efficiency of production can be further improved and contribute to the sustainability of the industry. Further sustainability in fertilizers could be found in integrating more organic nutrient sources.

Working with nutrients is a complex aspect of crop management. To ensure you get the highest quality crops, contact our FaaS team for expert insight and dependable help.